[PATCH] RME HDSPM MADI lock fix

[PATCH] RME HDSPM MADI lock fix

[Jörn Nettingsmeier]

[-- Attachment #1: Type: text/plain, Size: 1941 bytes --]

hi *!

while we were trying to debug the midi-related xruns in the current 
driver, i came across what looks like an unrelated locking bug to me:

static int snd_hdspm_midi_input_read (struct hdspm_midi *hmidi)
...
         spin_lock_irqsave (&hmidi->lock, flags); <---------------
         n_pending = snd_hdspm_midi_input_available (hmidi->hdspm, 
hmidi->id);
         if (n_pending > 0) {
                 if (hmidi->input) {
                         if (n_pending > (int)sizeof (buf))
                                 n_pending = sizeof (buf);
                         for (i = 0; i < n_pending; ++i)
                                 buf[i] = snd_hdspm_midi_read_byte 
(hmidi->hdspm,
 
hmidi->id);
                         if (n_pending)
                                 snd_rawmidi_receive (hmidi->input, buf,
                                                      n_pending);
                 } else {
                         /* flush the MIDI input FIFO */
                         while (n_pending--)
                                 snd_hdspm_midi_read_byte (hmidi->hdspm,
                                                           hmidi->id);
                 }
         }
         hmidi->pending = 0;

         hmidi->hdspm->control_register |= hmidi->ie;<------- !!!
         hdspm_write(hmidi->hdspm, HDSPM_controlRegister,
                     hmidi->hdspm->control_register);

         spin_unlock_irqrestore (&hmidi->lock, flags);<---------
         return snd_hdspm_midi_output_write (hmidi);
}


if i understand this whole business correctly, we should be holding the 
hdspm lock here, not the hmidi one.

please review the attached patch and apply if you think it's ok.


best,


jörn



-- 
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister (VDT)

http://stackingdwarves.net

[-- Attachment #2: hdspm-lockfix.diff --]
[-- Type: text/x-patch, Size: 663 bytes --]

--- sound/pci/rme9652/hdspm.c~	2011-06-01 21:30:24.000000000 +0200
+++ sound/pci/rme9652/hdspm.c	2011-06-01 22:04:08.184946711 +0200
@@ -1619,7 +1619,7 @@
 	int n_pending;
 	int i;
 
-	spin_lock_irqsave (&hmidi->lock, flags);
+	spin_lock_irqsave (&hmidi->hdspm->lock, flags);
 	n_pending = snd_hdspm_midi_input_available (hmidi->hdspm, hmidi->id);
 	if (n_pending > 0) {
 		if (hmidi->input) {
@@ -1644,7 +1644,7 @@
 	hdspm_write(hmidi->hdspm, HDSPM_controlRegister,
 		    hmidi->hdspm->control_register);
 
-	spin_unlock_irqrestore (&hmidi->lock, flags);
+	spin_unlock_irqrestore (&hmidi->hdspm->lock, flags);
 	return snd_hdspm_midi_output_write (hmidi);
 }
 

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Re: [PATCH] RME HDSPM MADI lock fix

[Takashi Iwai]

At Sun, 05 Jun 2011 11:57:57 +0200,
Jörn Nettingsmeier wrote:
> 
> hi *!
> 
> while we were trying to debug the midi-related xruns in the current 
> driver, i came across what looks like an unrelated locking bug to me:
> 
> static int snd_hdspm_midi_input_read (struct hdspm_midi *hmidi)
> ...
>          spin_lock_irqsave (&hmidi->lock, flags); <---------------
>          n_pending = snd_hdspm_midi_input_available (hmidi->hdspm, 
> hmidi->id);
>          if (n_pending > 0) {
>                  if (hmidi->input) {
>                          if (n_pending > (int)sizeof (buf))
>                                  n_pending = sizeof (buf);
>                          for (i = 0; i < n_pending; ++i)
>                                  buf[i] = snd_hdspm_midi_read_byte 
> (hmidi->hdspm,
>  
> hmidi->id);
>                          if (n_pending)
>                                  snd_rawmidi_receive (hmidi->input, buf,
>                                                       n_pending);
>                  } else {
>                          /* flush the MIDI input FIFO */
>                          while (n_pending--)
>                                  snd_hdspm_midi_read_byte (hmidi->hdspm,
>                                                            hmidi->id);
>                  }
>          }
>          hmidi->pending = 0;
> 
>          hmidi->hdspm->control_register |= hmidi->ie;<------- !!!
>          hdspm_write(hmidi->hdspm, HDSPM_controlRegister,
>                      hmidi->hdspm->control_register);
> 
>          spin_unlock_irqrestore (&hmidi->lock, flags);<---------
>          return snd_hdspm_midi_output_write (hmidi);
> }
> 
> 
> if i understand this whole business correctly, we should be holding the 
> hdspm lock here, not the hmidi one.
> 
> please review the attached patch and apply if you think it's ok.

Well, it's a wrong lock for snd_hdspm_midi_input_available().
So you'll need to lock twice, either once unlock and lock another or
nested.  Re-locking would be less messy in this case, I suppose.


thanks,

Takashi

> 
> 
> best,
> 
> 
> jörn
> 
> 
> 
> -- 
> Jörn Nettingsmeier
> Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487
> 
> Meister für Veranstaltungstechnik (Bühne/Studio)
> Tonmeister (VDT)
> 
> http://stackingdwarves.net
> [2 hdspm-lockfix.diff <text/x-patch (7bit)>]
> --- sound/pci/rme9652/hdspm.c~	2011-06-01 21:30:24.000000000 +0200
> +++ sound/pci/rme9652/hdspm.c	2011-06-01 22:04:08.184946711 +0200
> @@ -1619,7 +1619,7 @@
>  	int n_pending;
>  	int i;
>  
> -	spin_lock_irqsave (&hmidi->lock, flags);
> +	spin_lock_irqsave (&hmidi->hdspm->lock, flags);
>  	n_pending = snd_hdspm_midi_input_available (hmidi->hdspm, hmidi->id);
>  	if (n_pending > 0) {
>  		if (hmidi->input) {
> @@ -1644,7 +1644,7 @@
>  	hdspm_write(hmidi->hdspm, HDSPM_controlRegister,
>  		    hmidi->hdspm->control_register);
>  
> -	spin_unlock_irqrestore (&hmidi->lock, flags);
> +	spin_unlock_irqrestore (&hmidi->hdspm->lock, flags);
>  	return snd_hdspm_midi_output_write (hmidi);
>  }
>  
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Re: [PATCH] RME HDSPM MADI lock fix

[Jörn Nettingsmeier]

[-- Attachment #1: Type: text/plain, Size: 1674 bytes --]

On 06/06/2011 11:05 AM, Takashi Iwai wrote:
> At Sun, 05 Jun 2011 11:57:57 +0200,
> Jörn Nettingsmeier wrote:
>>
>> hi *!
>>
>> while we were trying to debug the midi-related xruns in the current
>> driver, i came across what looks like an unrelated locking bug to me:
>>
>> static int snd_hdspm_midi_input_read (struct hdspm_midi *hmidi)
>> ...
>>           spin_lock_irqsave (&hmidi->lock, flags);<---------------
>>           n_pending = snd_hdspm_midi_input_available (hmidi->hdspm,
>> hmidi->id);
>> ...
>>           hmidi->pending = 0;
>>
>>           hmidi->hdspm->control_register |= hmidi->ie;<------- !!!
>>           hdspm_write(hmidi->hdspm, HDSPM_controlRegister,
>>                       hmidi->hdspm->control_register);
>>
>>           spin_unlock_irqrestore (&hmidi->lock, flags);<---------
>>           return snd_hdspm_midi_output_write (hmidi);
>> }
>>
>>
>> if i understand this whole business correctly, we should be holding the
>> hdspm lock here, not the hmidi one.
>>
>> please review the attached patch and apply if you think it's ok.
>
> Well, it's a wrong lock for snd_hdspm_midi_input_available().
> So you'll need to lock twice, either once unlock and lock another or
> nested.  Re-locking would be less messy in this case, I suppose.

ok, here's a revised patch. has been running for 20 or so hours without 
problems, although the load was light most of the time.

please consider for inclusion.


best,


jörn



-- 
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister (VDT)

http://stackingdwarves.net

[-- Attachment #2: hdspm-lock-fix.diff --]
[-- Type: text/x-patch, Size: 612 bytes --]

--- linux-2.6.39/sound/pci/rme9652/hdspm.c.orig	2011-05-19 06:06:34.000000000 +0200
+++ linux-2.6.39/sound/pci/rme9652/hdspm.c	2011-06-07 10:26:35.778933230 +0200
@@ -1639,12 +1639,14 @@
 		}
 	}
 	hmidi->pending = 0;
+	spin_unlock_irqrestore (&hmidi->lock, flags);
 
+	spin_lock_irqsave (&hmidi->hdspm->lock, flags);
 	hmidi->hdspm->control_register |= hmidi->ie;
 	hdspm_write(hmidi->hdspm, HDSPM_controlRegister,
 		    hmidi->hdspm->control_register);
+	spin_unlock_irqrestore (&hmidi->hdspm->lock, flags);
 
-	spin_unlock_irqrestore (&hmidi->lock, flags);
 	return snd_hdspm_midi_output_write (hmidi);
 }
 

[-- Attachment #3: Type: text/plain, Size: 0 bytes --]

Re: [PATCH] RME HDSPM MADI lock fix

[Adrian Knoth]

On Tue, Jun 07, 2011 at 10:33:55AM +0200, Jörn Nettingsmeier wrote:

> --- linux-2.6.39/sound/pci/rme9652/hdspm.c.orig	2011-05-19 06:06:34.000000000 +0200
> +++ linux-2.6.39/sound/pci/rme9652/hdspm.c	2011-06-07 10:26:35.778933230 +0200
> @@ -1639,12 +1639,14 @@
>  		}
>  	}
>  	hmidi->pending = 0;
> +	spin_unlock_irqrestore (&hmidi->lock, flags);
>  
> +	spin_lock_irqsave (&hmidi->hdspm->lock, flags);
>  	hmidi->hdspm->control_register |= hmidi->ie;
>  	hdspm_write(hmidi->hdspm, HDSPM_controlRegister,
>  		    hmidi->hdspm->control_register);
> +	spin_unlock_irqrestore (&hmidi->hdspm->lock, flags);
>  
> -	spin_unlock_irqrestore (&hmidi->lock, flags);
>  	return snd_hdspm_midi_output_write (hmidi);
>  }
>  


This looks sane to me. I'll add it to my git repo and will re-post it
together with the upcoming changes for the iosono guys once we're
finished.


Cheers

-- 
mail: adi@thur.de  	http://adi.thur.de	PGP/GPG: key via keyserver

Re: [PATCH] RME HDSPM MADI lock fix

[Takashi Iwai]

At Tue, 07 Jun 2011 10:33:55 +0200,
Jörn Nettingsmeier wrote:
> 
> On 06/06/2011 11:05 AM, Takashi Iwai wrote:
> > At Sun, 05 Jun 2011 11:57:57 +0200,
> > Jörn Nettingsmeier wrote:
> >>
> >> hi *!
> >>
> >> while we were trying to debug the midi-related xruns in the current
> >> driver, i came across what looks like an unrelated locking bug to me:
> >>
> >> static int snd_hdspm_midi_input_read (struct hdspm_midi *hmidi)
> >> ...
> >>           spin_lock_irqsave (&hmidi->lock, flags);<---------------
> >>           n_pending = snd_hdspm_midi_input_available (hmidi->hdspm,
> >> hmidi->id);
> >> ...
> >>           hmidi->pending = 0;
> >>
> >>           hmidi->hdspm->control_register |= hmidi->ie;<------- !!!
> >>           hdspm_write(hmidi->hdspm, HDSPM_controlRegister,
> >>                       hmidi->hdspm->control_register);
> >>
> >>           spin_unlock_irqrestore (&hmidi->lock, flags);<---------
> >>           return snd_hdspm_midi_output_write (hmidi);
> >> }
> >>
> >>
> >> if i understand this whole business correctly, we should be holding the
> >> hdspm lock here, not the hmidi one.
> >>
> >> please review the attached patch and apply if you think it's ok.
> >
> > Well, it's a wrong lock for snd_hdspm_midi_input_available().
> > So you'll need to lock twice, either once unlock and lock another or
> > nested.  Re-locking would be less messy in this case, I suppose.
> 
> ok, here's a revised patch. has been running for 20 or so hours without 
> problems, although the load was light most of the time.
> 
> please consider for inclusion.

Looks good.  But please give a proper changelog and your sign-off
for inclusion.


thanks,

Takashi
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Re: [PATCH] RME HDSPM MADI lock fix

[Adrian Knoth]

On 06/07/2011 11:28 AM, Takashi Iwai wrote:

>>> Well, it's a wrong lock for snd_hdspm_midi_input_available().
>>> So you'll need to lock twice, either once unlock and lock another or
>>> nested.  Re-locking would be less messy in this case, I suppose.
>> ok, here's a revised patch. has been running for 20 or so hours without 
>> problems, although the load was light most of the time.
>>
>> please consider for inclusion.
> 
> Looks good.  But please give a proper changelog and your sign-off
> for inclusion.

I've handled this. I take care of everything, commit (with changelog and
sign-off) to my git repo and will send the final patch series to the
list once it's ready.


Cheers

Re: [PATCH] RME HDSPM MADI lock fix

[Takashi Iwai]

At Tue, 07 Jun 2011 11:30:28 +0200,
Adrian Knoth wrote:
> 
> On 06/07/2011 11:28 AM, Takashi Iwai wrote:
> 
> >>> Well, it's a wrong lock for snd_hdspm_midi_input_available().
> >>> So you'll need to lock twice, either once unlock and lock another or
> >>> nested.  Re-locking would be less messy in this case, I suppose.
> >> ok, here's a revised patch. has been running for 20 or so hours without 
> >> problems, although the load was light most of the time.
> >>
> >> please consider for inclusion.
> > 
> > Looks good.  But please give a proper changelog and your sign-off
> > for inclusion.
> 
> I've handled this. I take care of everything, commit (with changelog and
> sign-off) to my git repo and will send the final patch series to the
> list once it's ready.

OK, thanks.

(Note that usually a patch always requires the sign-off of the
 original author, no matter who commits.  But in this case, it doesn't
 matter much because the patch is trivial.)


Takashi

Re: [PATCH] RME HDSPM MADI lock fix

[Adrian Knoth]

On 06/07/2011 11:37 AM, Takashi Iwai wrote:

>>> Looks good.  But please give a proper changelog and your sign-off
>>> for inclusion.
>>
>> I've handled this. I take care of everything, commit (with changelog and
>> sign-off) to my git repo and will send the final patch series to the
>> list once it's ready.
> 
> OK, thanks.
> 
> (Note that usually a patch always requires the sign-off of the
>  original author, no matter who commits.  But in this case, it doesn't
>  matter much because the patch is trivial.)

That's exactly how I did it: Sign-off by Jörn and a second line by me.

Since it's his work and we're not talking about cryptographic
signatures, I took the liberty to provide the correct attribution.


Cheers